<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="/webjars/bootstrap/4.3.0/css/bootstrap.css">
    <script src="/webjars/jquery/3.4.0/jquery.js"></script>
    <script src="/webjars/bootstrap/4.3.0/js/bootstrap.js"></script>
</head>
<body>
<h2>Hello oauth2</h2>
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModalCenter">
    Launch demo modal 莽
</button>
<!-- Modal -->
<div class="modal fade" id="exampleModalCenter" tabindex="-1" role="dialog" aria-labelledby="exampleModalCenterTitle" aria-hidden="true">
    <div class="modal-dialog modal-dialog-centered" role="document">
        <div class="modal-content">
            <div class="modal-header">
                <h5 class="modal-title" id="exampleModalCenterTitle">Modal title</h5>
                <button type="button" class="close" data-dismiss="modal" aria-label="Close">
                    <span aria-hidden="true">&times;</span>
                </button>
            </div>
            <div class="modal-body">
                ...
            </div>
            <div class="modal-footer">
                <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
                <button type="button" class="btn btn-primary">Save changes</button>
            </div>
        </div>
    </div>
</div>
</body>
</html>
<script>
    $(function() {
        alert("ok");
    })
</script>